What changed was that the Lord revealed to His prophet that the practice of polygamy was to end. The covenants entered into by those who had practiced it are and were everlasting. The covenant is everlasting, not the practice of polygamy.
We believe today that the covenants entered into between God and man in the Holy Temple are everlasting. There is no polygamy involved, but the covenant and its nature are the same.
You are side stepping the issue. What was happening in 1890 that preceeded Wilson's declaration? We can explore what happens in the temple later.